Interpretive Summary: Spray drift from the aerial application of pesticides has been recognized as a concern for the environment. Aerial applicators can reduce incidents of spray drift and associated off-target damage by judicious selection of spray nozzles and application conditions to increase spray droplet size and reduce the driftable fine droplet component of the spray. Use of spray additives is an additional tool that applicators can use to reduce spray drift. Field studies were conducted to measure the effectiveness of several commercially-available spray additives on improving spray droplet size distribution, enhancing deposition, and reducing spray drift. Most of the spray additives reduced the amount of fine spray droplets that are prone to drift from the application site. The results show that aerial applicators can reduce spray drift by selecting and using effective spray additives, thereby reducing environmental impact in non-targeted areas.

Technical Abstract:
Numerous drift reduction adjuvants and spray deposition aids are available to applicators of crop production and protection chemicals. Performance of many of the newly introduced drift control adjuvants has not been well documented for aerial application. Five new drift control adjuvants were selected for drift studies in aerial applications. Deposition, downwind drift, and droplet spectra characteristics in a cotton canopy were collected on water sensitive paper (WSP) and Mylar cards for measurement and analysis. The deposition, droplet size, droplet coverage, and total drops were highly correlated to the drift distance and treatments or adjuvants. Deposition on the monofilament lines decreased as sampling height increased for each treatment. The results will aid aerial applicators in selecting drift reduction agents to meet the drift mitigation criterion for a given application.